The Nature of the Bonding and Valency for Oxygen in Its Metal Compounds

Abstract

The proposition: Within metal-oxygen compounds the valence of the metal is limited to + 3 or less, and unpaired electrons of the zero and minus-one valence states of oxygen are stabilized via pairing to the partially filled d-subshells of transition metals (with formation of d-p covalent bonds). The redox thermodynamics for the various transition metals and for the 0,−1, and −2 valence states of oxygen provide compelling evidence that the electron affinity for the d⁵−electrons in manganese(II) is substantially greater than it is for the p⁶−electrons in O². This prompts the formulation of permanganate ion as Mn¹¹()(O⁻·)⁻ ₃ rather than Mn^VII(O^2-)⁻ _4-; the former formulation is believed to be a more accurate representation of charge density, bond energies, and chemical reactivity. Similar arguments and conclusions are made for the oxygen compounds of other transition metal ions, including the active forms of horseradish peroxidase (Compounds I and II) and of cytochrome P-450. Likewise, the surface compounds of transition metals have properties that are consistent with zero-valent systems and covalent bonds; e.g.,